Sprinkler heads incorporating free-spinning water-distribution plates are well known in the art as evidenced by, for example, U.S. Pat. Nos. 5,042,720 and 7,025,287. Free-spinning sprinkler devices create gentle and small droplets that can be distributed evenly across the water pattern. Other sprinklers have been designed that incorporate viscously-damped rotor plates or gear-driven rotor plates that slow the rotation of the plate as compared to a free-spinning plate. See, for example, U.S. Pat. Nos. Re. 33,823 and 3,854,664. Water-distribution or rotor plates that are slowed by whatever means, produce defined water streams with greater radius of throw and relatively larger droplets. It will be appreciated that there are suitable applications for both types of sprinklers, depending on a variety of factors.
For mechanical move irrigation systems, where the sprinkler is moving over the field, gentle and smaller water droplets are preferred at times. For example, during irrigation over bare ground or when germinating a seed piece, the gentler, smaller droplets produced from a free-spinning sprinkler do not disturb the seed piece or detrimentally impact or displace the soil structure. After the crop is established, however, and the soil surface is covered with foliage, a larger droplet is preferred to penetrate through the wind and maximize the amount of water that reaches the crop.